Предмет: Физика, автор: KotenokQQ

Какую силу нужно приложить к деревянному бруску объёмом 300 см3 (в кубе) находящемуся под водой, чтобы не давать ему всплывать. Плотность воды 1000 кгм3 плотность дерева 400 кгм3
СРОЧНО!!!1!

Ответы

Автор ответа: elena20092

Ответ:

Сила должна быть больше или равна 1,8 Н

Объяснение:

V = 300 см³ = 3·10⁻⁴ м³

ρ₁ = 1000 кг/м³ - плотность воды

ρ₂ = 400 кг/м³ - плотность дерева

g = 10 Н/кг - ускорение свободного падения

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F - ?

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Сила, прикладываемая, к бруску, чтобы удержать его под водой, больше или равна разности выталкивающей архимедовой силы Fа = ρ₁ · g · V и силы тяжести бруска Р = ρ₂ · g · V

F ≥ Fa - P

F ≥ ρ₁ · g · V - ρ₂ · g · V

F ≥ g · V · (ρ₁ ·- ρ₂)

F ≥ 10 · 3·10⁻⁴ · (1000 ·- 400)

F ≥ 1.8 (H)

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